The episode opens the morning before a Subdigitals concert. Aelita, who has won a contest to be the band's opening act, is harassed throughout the day by fans and critics alike, and reveals to her friends that she is nervous and scared of performing in front of a large audience. However, when she turns to Jeremie for support, he is engrossed in searching for new Replikas, and is not willing to stop working to attend her concert. Hurt, Aelita lashes out at him and cries.
That night, a large crowd gathers at the concert venue, and Aelita prepares in her dressing room. Jeremie remains in his dorm room working until Yumi calls him just before the concert starts and convinces him to make an appearance for Aelita's sake. However, just before Jeremie leaves, the Superscan detects an activated a tower in the Mountain Sector, and X.A.N.A. sends a spectre to the concert. Backstage, Sophie, the Subdigitals' manager, is possessed by the spectre, and attacks Aelita before instructing the Subdigitals to go on without her. Yumi, Odd, an Ulrich are confused by Aelita's absence until Jeremie calls them to inform them of the X.A.N.A. attack.
As Jeremie arrives at the Factory, Ulrich, Odd, and Yumi force their way backstage to find Sophie leaving the building with an unconscious Aelita. However, before the trio can pursue her, they are intercepted by Milly and Tamiya, who are revealed to be possessed as well. Ulrich volunteers to fend the girls off while Yumi and Odd escape. Yumi then calls Jeremie and informs him of the kidnapping, correctly deducing that Sophie is taking Aelita to the Factory. Jeremie tries in vein to stop Sophie on the main floor, and she then virtualizes Aelita, still unconscious, onto Lyoko.
Odd and Yumi arrive at the Factory to find Sophie in the Lab. The two work together to incapacitate the woman while Aelita fends off several monsters until William appears, forcing her to retreat. Jeremie then arrives in the Lab and sends Yumi and Odd to Lyoko, where a battle ensues. As Ulrich continues to fend off Milly and Tamiya backstage, Yumi, Odd, and William dogfight using the Overwing, the Overboard, and the Black Manta, respectively.
As Aelita wakes up and battles monsters in front of the tower, Sophie regains consciousness as well and attacks Jeremie. After taking control of the interface, Sophie devirtualizes Yumi and Odd's vehicles, and Yumi sacrifices herself to defeat William. Odd then arrives at the tower and defeats the remaining monsters, allowing Aelita to deactivate it, saving Jeremie from Sophie and Ulrich from Milly and Tamiya. Jeremie then performs a Time Reversion, bringing them back to before the concert.
In Aelita's dressing room, Jeremie arrives and wishes Aelita luck. Aelita then apologizes for lashing out at him earlier that day, and Jeremie apologizes for missing the concert the first time. Then, once the concert starts, Aelita comes out on stage and performs well, having seemingly beaten her stage fright.
- The original French name for this episode is Il est sensé d'être insensé, which translates loosely to It's Sane to Be Insane, a reference to a line Jeremie says to Aelita near the end of the episode.
- This is the only episode in which Alain le Dong, a long-time storyboard creator, is credited as a writer.
The original episode summary can be found here.